I am not so sure if this is correct. To my knowledge, BTC processes, as opposed to DIA, never perform "roll out" (e.g. during an RFC call) but just wait until processing continues. I just made a quick test in NW 740 release, there the BTC process remains occupied by my job when it does WAIT UP TO xxx SECONDS. So you occupy one BTC process as long as your job runs.
Please try out yourself and then award points to whoever is right, please.
Regards,
Alex